From e5cb8f1ef60c36d29d66bf8dbb25365423b9b3c8 Mon Sep 17 00:00:00 2001 From: Alan Pearce Date: Tue, 24 Oct 2017 12:04:46 +0200 Subject: Add fp-js talk --- static/talks/fp-js/s5-blank.html | 50 +++ static/talks/fp-js/slides.html | 431 ++++++++++++++++++++++ static/talks/fp-js/slides.org | 226 ++++++++++++ static/talks/fp-js/ui/default/blank.gif | Bin 0 -> 49 bytes static/talks/fp-js/ui/default/bodybg.gif | Bin 0 -> 10119 bytes static/talks/fp-js/ui/default/framing.css | 23 ++ static/talks/fp-js/ui/default/iepngfix.htc | 42 +++ static/talks/fp-js/ui/default/opera.css | 7 + static/talks/fp-js/ui/default/outline.css | 15 + static/talks/fp-js/ui/default/pretty.css | 86 +++++ static/talks/fp-js/ui/default/print.css | 1 + static/talks/fp-js/ui/default/s5-core.css | 9 + static/talks/fp-js/ui/default/slides.css | 3 + static/talks/fp-js/ui/default/slides.js | 553 +++++++++++++++++++++++++++++ 14 files changed, 1446 insertions(+) create mode 100644 static/talks/fp-js/s5-blank.html create mode 100644 static/talks/fp-js/slides.html create mode 100644 static/talks/fp-js/slides.org create mode 100644 static/talks/fp-js/ui/default/blank.gif create mode 100755 static/talks/fp-js/ui/default/bodybg.gif create mode 100644 static/talks/fp-js/ui/default/framing.css create mode 100644 static/talks/fp-js/ui/default/iepngfix.htc create mode 100644 static/talks/fp-js/ui/default/opera.css create mode 100644 static/talks/fp-js/ui/default/outline.css create mode 100644 static/talks/fp-js/ui/default/pretty.css create mode 100644 static/talks/fp-js/ui/default/print.css create mode 100644 static/talks/fp-js/ui/default/s5-core.css create mode 100644 static/talks/fp-js/ui/default/slides.css create mode 100644 static/talks/fp-js/ui/default/slides.js (limited to 'static') diff --git a/static/talks/fp-js/s5-blank.html b/static/talks/fp-js/s5-blank.html new file mode 100644 index 0000000..0d126c7 --- /dev/null +++ b/static/talks/fp-js/s5-blank.html @@ -0,0 +1,50 @@ + + + + + +Functional Programming + + + + + + + + + + + + + + + + + + + +
+
+
+ + + +
+ + +
+ +
+

Functional Programming

+

in JavaScript

+

Alan Pearce

+
+ + +
+ + + diff --git a/static/talks/fp-js/slides.html b/static/talks/fp-js/slides.html new file mode 100644 index 0000000..e90650c --- /dev/null +++ b/static/talks/fp-js/slides.html @@ -0,0 +1,431 @@ + + + + + + +Functional Programming in JavaScript + + + + + + + + + + + + + + + + +
+
+
+ + + + +
+
+
+

Functional Programming in JavaScript

+

+

Alan Pearce

+

alan@alanpearce.eu

+

+
+
+

Table of Contents

+
+
    +
  • 1. Why?
  • +
  • 2. Concepts
  • +
  • 3. Further concepts
  • +
  • 4. First-class functions
  • +
  • 5. Higher-order functions
  • +
  • 6. Higher-order functions (cont.)
  • +
  • 7. Pure functions
  • +
  • 8. Recursion
  • +
  • 9. Partial application
  • +
  • 10. Partial application (cont.)
  • +
  • 11. Currying
  • +
  • 12. Easy Currying
  • +
  • 13. Practical Currying
  • +
  • 14. Functional composition
  • +
  • 15. Functional composition (cont.)
  • +
  • 16. pipe
  • +
  • 17. Point-free programming
  • +
  • 18. Further Resources
  • +
+
+
+ +
+

1 Why?

+
+

+Imperative programming is concerned with how +

+ +

+Functional programming is concerned with what +

+
+
+ +
+

2 Concepts

+
+
    +
  • First-class Functions
  • +
  • Higher-order Functions
  • +
  • Recursion
  • +
  • Pure functions
  • +
  • Currying & Partial Application
  • +
+
+
+ +
+

3 Further concepts

+
+
    +
  • Lazy Evaluation
  • +
  • Types & Data Structures
  • +
  • Category Theory
  • +
+
+
+ +
+

4 First-class functions

+
+
    +
  • Are values
  • +
  • Have no restriction on their use
  • +
  • Enable the use of callback functions in JavaScript
  • +
+ +

+ +

+ +
+
var fn = function () {
+  return 2
+}
+
+
+
+
+ + +
+

5 Higher-order functions

+
+

+Functions that operate on other functions are higher-order functions +

+ +

+ +

+ +
+
var succ = function (x) {
+  return x + 1
+}
+
+var arr = [1, 2, 3, 4]
+
+arr.map(succ)
+
+
+ +

+Here, Array.prototype.map is the higher-order function +

+
+
+ +
+

6 Higher-order functions (cont.)

+
+

+Functions that return functions are also higher-order functions +

+ +

+ +

+ +
+
function adder (n) {
+  return function (x) {
+    return n + x
+  }
+}
+
+var add1 = adder(1)
+
+
+ +

+adder is a higher-order function +

+
+
+ +
+

7 Pure functions

+
+

+Functions without side-effects +

+ +
+
var succ = (x) => x + 1
+
+console.log(succ(succ(1)))
+
+// could be optimised away by a compiler, e.g.:
+
+console.log(3)
+
+
+
+
+ +
+

8 Recursion

+
+

+Functions that call themselves +

+ +
+
function fibonacci (n) {
+  switch (n) {
+    case 0:
+    case 1:
+      return 1
+    default: 
+      return fibonacci(n - 1) + fibonacci(n - 2)
+  }
+}
+
+
+
+
+ +
+

9 Partial application

+
+

+The infamous Function.prototype.bind in JavaScript +

+ +
+
function add (x, y) {
+  return x + y
+}
+
+var add1 = add.bind(add, 1)
+
+add1(3) // = 4
+
+
+
+
+ +
+

10 Partial application (cont.)

+
+

+After ES6 introduced arrow functions, partial application has become +more popular +

+ +
+
var add = x => y => x + y
+
+
+
+
+ +
+

11 Currying

+
+

+Related to partial application, but more implicit and general +

+ +

+Translates 1 function of arity n to n functions of arity 1 +

+ +
+
function volume (w, d, h) {
+  return w * d * h
+}
+
+var vol = curry(volume)
+vol(10)(20)(30)
+// is strictly equivalent to
+volume(10, 20, 30)
+
+
+
+
+ +
+

12 Easy Currying

+
+

+In order to make currying (and partial application) easier to use, +move the most important argument to a function to the end: +

+ +
+
var badMap = (arr, fn) => arr.map(fn)
+var goodMap = (fn, arr) => arr.map(fn)
+var curriedBadMap = curry(badmap)
+var curriedGoodMap = curry(goodMap)
+
+var goodDoubleArray = goodMap(x => x * 2)
+var badDoubleArray = badMap(_, x => x * 2)
+
+
+ +

+The bad version requires the curry function to support a magic +placeholder argument and doesn't look as clean. +

+
+
+ +
+

13 Practical Currying

+
+

+Currying is not automatic in JavaScript, as in other languages +

+ +

+External tools aren't (so far) able to statically analyse curried +functions +

+ +

+Solution: Don't expose curried functions +Instead, write functions as if currying were automatic +

+ +

+If consumers want to curry, they can. If they don't, their editor or +language server will show them the arguments +

+
+
+ +
+

14 Functional composition

+
+

+Creating functions from other functions +

+ +

+Usually provided by compose (right-to-left) and pipe (left-to-right) +

+ +

+A very simple definition of compose for only two functions would look like this +

+ +
+
function compose (f, g) {
+  return function (...args) {
+    return f(g(...args))
+  }
+}
+
+
+
+
+ +
+

15 Functional composition (cont.)

+
+
+
var plusOne = x => x + 1
+var timesTwo = x => x * 2
+
+var plusOneTimesTwo = compose(timesTwo, plusOne)
+var timesTwoPlusOne = compose(plusOne, timesTwo)
+
+nextDoubled(3) // = (3 + 1) * 2 = 8
+doubledPlusOne(3) // = (3 * 2) + 1 = 7
+
+
+
+
+ +
+

16 pipe

+
+

+What about pipe? +

+ +

+pipe does the same thing, but runs the functions the other way around +

+ +

+pipe(f, g) is the same as compose(g, f) +

+
+
+ +
+

17 Point-free programming

+
+

+With currying and higher-order functions, we (often) don't need to declare function arguments +

+ +
+
var modulo = a => b => b % a
+var eq = a => b => a === b
+
+var isEven = x => eq(0)(modulo(2)(x))
+var isEvenPointFree = compose(eq(0), modulo(2))
+
+
+
+
+ +
+

18 Further Resources

+
+ +
+
+ + +
+ + diff --git a/static/talks/fp-js/slides.org b/static/talks/fp-js/slides.org new file mode 100644 index 0000000..8a4bf6c --- /dev/null +++ b/static/talks/fp-js/slides.org @@ -0,0 +1,226 @@ +#+TITLE: Functional Programming in JavaScript +#+PROPERTY: :html-toplevel-hlevel 1 +#+PROPERTY: :with-toc 0 +* Why? + +Imperative programming is concerned with *how* + +Functional programming is concerned with *what* + +* Concepts + + - First-class Functions + - Higher-order Functions + - Recursion + - Pure functions + - Currying & Partial Application + +* Further concepts + + - Lazy Evaluation + - Types & Data Structures + - Category Theory + +* First-class functions + + - Have no restriction on their use + - Are values + - Enable the use of callback functions in JavaScript + + + +#+BEGIN_SRC js +const fn = function () { + return 2 +} +#+END_SRC + + +* Higher-order functions + +Functions that operate on other functions are higher-order functions + + + +#+BEGIN_SRC js +const succ = function (x) { + return x + 1 +} + +const arr = [1, 2, 3, 4] + +arr.map(succ) +#+END_SRC + +Here, =Array.prototype.map= is the higher-order function + +* Higher-order functions (cont.) + +Functions that return functions are also higher-order functions + + + +#+BEGIN_SRC js +function adder (n) { + return function (x) { + return n + x + } +} + +const add1 = adder(1) +#+END_SRC + +=adder= is a higher-order function + +* Pure functions + +Functions without side-effects + +#+BEGIN_SRC js +const succ = (x) => x + 1 + +console.log(succ(succ(1))) + +// could be optimised away by a compiler, e.g.: + +console.log(3) +#+END_SRC + +* Recursion + +Functions that call themselves + +#+BEGIN_SRC js +function fibonacci (n) { + switch (n) { + case 0: + case 1: + return 1 + default: + return fibonacci(n - 1) + fibonacci(n - 2) + } +} +#+END_SRC + +* Partial application + +The infamous =Function.prototype.bind= in JavaScript + +#+BEGIN_SRC js +function add (x, y) { + return x + y +} + +const add1 = add.bind(add, 1) + +add1(3) // = 4 +#+END_SRC + +* Partial application (cont.) + +After ES6 introduced arrow functions, partial application has become +more popular + +#+BEGIN_SRC js +const add = x => y => x + y +#+END_SRC + +* Currying + +Related to partial application, but more implicit and general + +Translates */1/ function of arity /n/* to */n/ functions of arity /1/* + +#+BEGIN_SRC js +function volume (w, d, h) { + return w * d * h +} + +const vol = curry(volume) +vol(10)(20)(30) +// is strictly equivalent to +volume(10, 20, 30) +#+END_SRC + +* Easy Currying + +In order to make currying (and partial application) easier to use, +move the *most important* argument to a function to the end: + +#+BEGIN_SRC js +const badMap = (arr, fn) => arr.map(fn) +const goodMap = (fn, arr) => arr.map(fn) +const curriedBadMap = curry(badmap) +const curriedGoodMap = curry(goodMap) + +const goodDoubleArray = goodMap(x => x * 2) +const badDoubleArray = badMap(_, x => x * 2) +#+END_SRC + +The bad version requires the curry function to support a magic +placeholder argument and doesn't look as clean. + +* Practical Currying + +Currying is not automatic in JavaScript, as in other languages + +External tools don't (currently) to statically analyse curried +functions + +Solution: Don't expose curried functions +Instead, write functions as if currying were automatic + +* Functional composition + +Creating functions from other functions + +Usually provided by =compose= (right-to-left) and =pipe= (left-to-right) + +A very simple definition of =compose= for only two functions would look like this + +#+BEGIN_SRC js +function compose (f, g) { + return function (...args) { + return f(g(...args)) + } +} +#+END_SRC + +* Functional composition (cont.) + +#+BEGIN_SRC js +const plusOne = x => x + 1 +const timesTwo = x => x * 2 + +const plusOneTimesTwo = compose(timesTwo, plusOne) +const timesTwoPlusOne = compose(plusOne, timesTwo) + +nextDoubled(3) // = (3 + 1) * 2 = 8 +timesTwoPlusOne(3) // = (3 * 2) + 1 = 7 +#+END_SRC + +* pipe + +What about =pipe=? + +=pipe= does the same thing, but runs the functions the other way around + +=pipe(f, g)= is the same as =compose(g, f)= + +* Point-free programming + +With currying and higher-order functions, we (often) don't need to declare function arguments + +#+BEGIN_SRC js +const modulo = a => b => b % a +const eq = a => b => a === b + +const isEven = x => eq(0)(modulo(2)(x)) +const isEvenPointFree = compose(eq(0), modulo(2)) +#+END_SRC + +* Further Resources + +- [[https://drboolean.gitbooks.io/mostly-adequate-guide/content/][Mostly adequate guide to FP (in javascript)]] +- [[http://ramdajs.com/][Ramda]], a general-purpose FP library +- [[https://sanctuary.js.org/][Sanctuary]], a JavaScript library for Haskellers diff --git a/static/talks/fp-js/ui/default/blank.gif b/static/talks/fp-js/ui/default/blank.gif new file mode 100644 index 0000000..75b945d Binary files /dev/null and b/static/talks/fp-js/ui/default/blank.gif differ diff --git 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DO NOT REMOVE IT! */ .slide, ul {page-break-inside: avoid; visibility: visible !important;} h1 {page-break-after: avoid;} body {font-size: 12pt; background: white;} * {color: black;} #slide0 h1 {font-size: 200%; border: none; margin: 0.5em 0 0.25em;} #slide0 h3 {margin: 0; padding: 0;} #slide0 h4 {margin: 0 0 0.5em; padding: 0;} #slide0 {margin-bottom: 3em;} h1 {border-top: 2pt solid gray; border-bottom: 1px dotted silver;} .extra {background: transparent !important;} div.extra, pre.extra, .example {font-size: 10pt; color: #333;} ul.extra a {font-weight: bold;} p.example {display: none;} #header {display: none;} #footer h1 {margin: 0; border-bottom: 1px solid; color: gray; font-style: italic;} #footer h2, #controls {display: none;} /* The following rule keeps the layout stuff out of print. Remove at your own risk! */ .layout, .layout * {display: none !important;} \ No newline at end of file diff --git a/static/talks/fp-js/ui/default/s5-core.css b/static/talks/fp-js/ui/default/s5-core.css new file mode 100644 index 0000000..86444e0 --- /dev/null +++ b/static/talks/fp-js/ui/default/s5-core.css @@ -0,0 +1,9 @@ +/* Do not edit or override these styles! The system will likely break if you do. */ + +div#header, div#footer, div#controls, .slide {position: absolute;} +html>body div#header, html>body div#footer, + html>body div#controls, html>body .slide {position: fixed;} +.handout {display: none;} +.layout {display: block;} +.slide, .hideme, .incremental {visibility: hidden;} +#slide0 {visibility: visible;} diff --git a/static/talks/fp-js/ui/default/slides.css b/static/talks/fp-js/ui/default/slides.css new file mode 100644 index 0000000..0786d7d --- /dev/null +++ b/static/talks/fp-js/ui/default/slides.css @@ -0,0 +1,3 @@ +@import url(s5-core.css); /* required to make the slide show run at all */ +@import url(framing.css); /* sets basic placement and size of slide components */ +@import url(pretty.css); /* stuff that makes the slides look better than blah */ \ No newline at end of file diff --git a/static/talks/fp-js/ui/default/slides.js b/static/talks/fp-js/ui/default/slides.js new file mode 100644 index 0000000..38fe853 --- /dev/null +++ b/static/talks/fp-js/ui/default/slides.js @@ -0,0 +1,553 @@ +// S5 v1.1 slides.js -- released into the Public Domain +// +// Please see http://www.meyerweb.com/eric/tools/s5/credits.html for information +// about all the wonderful and talented contributors to this code! + +var undef; +var slideCSS = ''; +var snum = 0; +var smax = 1; +var incpos = 0; +var number = undef; +var s5mode = true; +var defaultView = 'slideshow'; +var controlVis = 'visible'; + +var isIE = navigator.appName == 'Microsoft Internet Explorer' && navigator.userAgent.indexOf('Opera') < 1 ? 1 : 0; +var isOp = navigator.userAgent.indexOf('Opera') > -1 ? 1 : 0; +var isGe = navigator.userAgent.indexOf('Gecko') > -1 && navigator.userAgent.indexOf('Safari') < 1 ? 1 : 0; + +function hasClass(object, className) { + if (!object.className) return false; + return (object.className.search('(^|\\s)' + className + '(\\s|$)') != -1); +} + +function hasValue(object, value) { + if (!object) return false; + return (object.search('(^|\\s)' + value + '(\\s|$)') != -1); +} + +function removeClass(object,className) { + if (!object) return; + object.className = object.className.replace(new RegExp('(^|\\s)'+className+'(\\s|$)'), RegExp.$1+RegExp.$2); +} + +function addClass(object,className) { + if (!object || hasClass(object, className)) return; + if (object.className) { + object.className += ' '+className; + } else { + object.className = className; + } +} + +function GetElementsWithClassName(elementName,className) { + var allElements = document.getElementsByTagName(elementName); + var elemColl = new Array(); + for (var i = 0; i< allElements.length; i++) { + if (hasClass(allElements[i], className)) { + elemColl[elemColl.length] = allElements[i]; + } + } + return elemColl; +} + +function isParentOrSelf(element, id) { + if (element == null || element.nodeName=='BODY') return false; + else if (element.id == id) return true; + else return isParentOrSelf(element.parentNode, id); +} + +function nodeValue(node) { + var result = ""; + if (node.nodeType == 1) { + var children = node.childNodes; + for (var i = 0; i < children.length; ++i) { + result += nodeValue(children[i]); + } + } + else if (node.nodeType == 3) { + result = node.nodeValue; + } + return(result); +} + +function slideLabel() { + var slideColl = GetElementsWithClassName('*','slide'); + var list = document.getElementById('jumplist'); + smax = slideColl.length; + for (var n = 0; n < smax; n++) { + var obj = slideColl[n]; + + var did = 'slide' + n.toString(); + obj.setAttribute('id',did); + if (isOp) continue; + + var otext = ''; + var menu = obj.firstChild; + if (!menu) continue; // to cope with empty slides + while (menu && menu.nodeType == 3) { + menu = menu.nextSibling; + } + if (!menu) continue; // to cope with slides with only text nodes + + var menunodes = menu.childNodes; + for (var o = 0; o < menunodes.length; o++) { + otext += nodeValue(menunodes[o]); + } + list.options[list.length] = new Option(n + ' : ' + otext, n); + } +} + +function currentSlide() { + var cs; + if (document.getElementById) { + cs = document.getElementById('currentSlide'); + } else { + cs = document.currentSlide; + } + cs.innerHTML = '' + snum + '<\/span> ' + + '\/<\/span> ' + + '' + (smax-1) + '<\/span>'; + if (snum == 0) { + cs.style.visibility = 'hidden'; + } else { + cs.style.visibility = 'visible'; + } +} + +function go(step) { + if (document.getElementById('slideProj').disabled || step == 0) return; + var jl = document.getElementById('jumplist'); + var cid = 'slide' + snum; + var ce = document.getElementById(cid); + if (incrementals[snum].length > 0) { + for (var i = 0; i < incrementals[snum].length; i++) { + removeClass(incrementals[snum][i], 'current'); + removeClass(incrementals[snum][i], 'incremental'); + } + } + if (step != 'j') { + snum += step; + lmax = smax - 1; + if (snum > lmax) snum = lmax; + if (snum < 0) snum = 0; + } else + snum = parseInt(jl.value); + var nid = 'slide' + snum; + var ne = document.getElementById(nid); + if (!ne) { + ne = document.getElementById('slide0'); + snum = 0; + } + if (step < 0) {incpos = incrementals[snum].length} else {incpos = 0;} + if (incrementals[snum].length > 0 && incpos == 0) { + for (var i = 0; i < incrementals[snum].length; i++) { + if (hasClass(incrementals[snum][i], 'current')) + incpos = i + 1; + else + addClass(incrementals[snum][i], 'incremental'); + } + } + if (incrementals[snum].length > 0 && incpos > 0) + addClass(incrementals[snum][incpos - 1], 'current'); + ce.style.visibility = 'hidden'; + ne.style.visibility = 'visible'; + jl.selectedIndex = snum; + currentSlide(); + number = 0; +} + +function goTo(target) { + if (target >= smax || target == snum) return; + go(target - snum); +} + +function subgo(step) { + if (step > 0) { + removeClass(incrementals[snum][incpos - 1],'current'); + removeClass(incrementals[snum][incpos], 'incremental'); + addClass(incrementals[snum][incpos],'current'); + incpos++; + } else { + incpos--; + removeClass(incrementals[snum][incpos],'current'); + addClass(incrementals[snum][incpos], 'incremental'); + addClass(incrementals[snum][incpos - 1],'current'); + } +} + +function toggle() { + var slideColl = GetElementsWithClassName('*','slide'); + var slides = document.getElementById('slideProj'); + var outline = document.getElementById('outlineStyle'); + if (!slides.disabled) { + slides.disabled = true; + outline.disabled = false; + s5mode = false; + fontSize('1em'); + for (var n = 0; n < smax; n++) { + var slide = slideColl[n]; + slide.style.visibility = 'visible'; + } + } else { + slides.disabled = false; + outline.disabled = true; + s5mode = true; + fontScale(); + for (var n = 0; n < smax; n++) { + var slide = slideColl[n]; + slide.style.visibility = 'hidden'; + } + slideColl[snum].style.visibility = 'visible'; + } +} + +function showHide(action) { + var obj = GetElementsWithClassName('*','hideme')[0]; + switch (action) { + case 's': obj.style.visibility = 'visible'; break; + case 'h': obj.style.visibility = 'hidden'; break; + case 'k': + if (obj.style.visibility != 'visible') { + obj.style.visibility = 'visible'; + } else { + obj.style.visibility = 'hidden'; + } + break; + } +} + +// 'keys' code adapted from MozPoint (http://mozpoint.mozdev.org/) +function keys(key) { + if (!key) { + key = event; + key.which = key.keyCode; + } + if (key.which == 84) { + toggle(); + return; + } + if (s5mode) { + switch (key.which) { + case 10: // return + case 13: // enter + if (window.event && isParentOrSelf(window.event.srcElement, 'controls')) return; + if (key.target && isParentOrSelf(key.target, 'controls')) return; + if(number != undef) { + goTo(number); + break; + } + case 32: // spacebar + case 34: // page down + case 39: // rightkey + case 40: // downkey + if(number != undef) { + go(number); + } else if (!incrementals[snum] || incpos >= incrementals[snum].length) { + go(1); + } else { + subgo(1); + } + break; + case 33: // page up + case 37: // leftkey + case 38: // upkey + if(number != undef) { + go(-1 * number); + } else if (!incrementals[snum] || incpos <= 0) { + go(-1); + } else { + subgo(-1); + } + break; + case 36: // home + goTo(0); + break; + case 35: // end + goTo(smax-1); + break; + case 67: // c + showHide('k'); + break; + } + if (key.which < 48 || key.which > 57) { + number = undef; + } else { + if (window.event && isParentOrSelf(window.event.srcElement, 'controls')) return; + if (key.target && isParentOrSelf(key.target, 'controls')) return; + number = (((number != undef) ? number : 0) * 10) + (key.which - 48); + } + } + return false; +} + +function clicker(e) { + number = undef; + var target; + if (window.event) { + target = window.event.srcElement; + e = window.event; + } else target = e.target; + if (target.getAttribute('href') != null || hasValue(target.rel, 'external') || isParentOrSelf(target, 'controls') || isParentOrSelf(target,'embed') || isParentOrSelf(target,'object')) return true; + if (!e.which || e.which == 1) { + if (!incrementals[snum] || incpos >= incrementals[snum].length) { + go(1); + } else { + subgo(1); + } + } +} + +function findSlide(hash) { + var target = null; + var slides = GetElementsWithClassName('*','slide'); + for (var i = 0; i < slides.length; i++) { + var targetSlide = slides[i]; + if ( (targetSlide.name && targetSlide.name == hash) + || (targetSlide.id && targetSlide.id == hash) ) { + target = targetSlide; + break; + } + } + while(target != null && target.nodeName != 'BODY') { + if (hasClass(target, 'slide')) { + return parseInt(target.id.slice(5)); + } + target = target.parentNode; + } + return null; +} + +function slideJump() { + if (window.location.hash == null) return; + var sregex = /^#slide(\d+)$/; + var matches = sregex.exec(window.location.hash); + var dest = null; + if (matches != null) { + dest = parseInt(matches[1]); + } else { + dest = findSlide(window.location.hash.slice(1)); + } + if (dest != null) + go(dest - snum); +} + +function fixLinks() { + var thisUri = window.location.href; + thisUri = thisUri.slice(0, thisUri.length - window.location.hash.length); + var aelements = document.getElementsByTagName('A'); + for (var i = 0; i < aelements.length; i++) { + var a = aelements[i].href; + var slideID = a.match('\#slide[0-9]{1,2}'); + if ((slideID) && (slideID[0].slice(0,1) == '#')) { + var dest = findSlide(slideID[0].slice(1)); + if (dest != null) { + if (aelements[i].addEventListener) { + aelements[i].addEventListener("click", new Function("e", + "if (document.getElementById('slideProj').disabled) return;" + + "go("+dest+" - snum); " + + "if (e.preventDefault) e.preventDefault();"), true); + } else if (aelements[i].attachEvent) { + aelements[i].attachEvent("onclick", new Function("", + "if (document.getElementById('slideProj').disabled) return;" + + "go("+dest+" - snum); " + + "event.returnValue = false;")); + } + } + } + } +} + +function externalLinks() { + if (!document.getElementsByTagName) return; + var anchors = document.getElementsByTagName('a'); + for (var i=0; i' + + '